i build a chat room its built by flash/actionscript that connects the server throuth aspx/vb.net

everyone that connects to the room with a username is listed in the users tablesince the server cant talk to the clienti have a function on the client (flash object) that sends a request to the server to get datathe data:a. new messagesb. new usersc. users that left the roomon every user request i update in the users table the time of the last requestthe request is made every 2 seconds

if a user use the logout buttoni can inform the server (using actionscript) to remove him from the users tablebut if he just closes the browserthe server cant know that this user is no longer connectedunless the server checks from time to time to see if some user dont request data anymore

therefore i have a field in the users table that is updated on every request by the time of the last request

and i want the server to check from time to time (lets say every 2 minutes) what was the last time of request of every userif their was no request for the last minutesthe user is not connected he closed the browser.